Sharable API

1 files changed, 271 insertions, 0 deletions

diff --git a/src/collection/retry.rs b/src/collection/retry.rs
new file mode 100644
index 0000000..3000f8b
--- /dev/null
+++ b/src/collection/retry.rs
@@ -0,0 +1,271 @@
+use crate::{lockable::Lock, Keyable, Lockable, OwnedLockable, Sharable};
+use std::collections::HashSet;
+use std::marker::PhantomData;
+
+use super::{LockGuard, RetryingLockCollection};
+
+fn contains_duplicates<L: Lockable>(data: L) -> bool {
+	let mut locks = Vec::new();
+	data.get_ptrs(&mut locks);
+	let locks = locks.into_iter().map(|l| l as *const dyn Lock);
+
+	let mut locks_set = HashSet::new();
+	for lock in locks {
+		if !locks_set.insert(lock) {
+			return true;
+		}
+	}
+
+	false
+}
+
+unsafe impl<L: Lockable> Lockable for RetryingLockCollection<L> {
+	type Guard<'g> = L::Guard<'g> where Self: 'g;
+
+	type ReadGuard<'g> = L::ReadGuard<'g> where Self: 'g;
+
+	fn get_ptrs<'a>(&'a self, ptrs: &mut Vec<&'a dyn Lock>) {
+		self.data.get_ptrs(ptrs)
+	}
+
+	unsafe fn guard(&self) -> Self::Guard<'_> {
+		self.data.guard()
+	}
+
+	unsafe fn read_guard(&self) -> Self::ReadGuard<'_> {
+		self.data.read_guard()
+	}
+}
+
+unsafe impl<L: Sharable> Sharable for RetryingLockCollection<L> {}
+
+unsafe impl<L: OwnedLockable> OwnedLockable for RetryingLockCollection<L> {}
+
+impl<L: OwnedLockable> RetryingLockCollection<L> {
+	#[must_use]
+	pub const fn new(data: L) -> Self {
+		Self { data }
+	}
+}
+
+impl<'a, L: OwnedLockable> RetryingLockCollection<&'a L> {
+	#[must_use]
+	pub const fn new_ref(data: &'a L) -> Self {
+		Self { data }
+	}
+}
+
+impl<L: Lockable> RetryingLockCollection<L> {
+	#[must_use]
+	pub const unsafe fn new_unchecked(data: L) -> Self {
+		Self { data }
+	}
+
+	pub fn try_new(data: L) -> Option<Self> {
+		contains_duplicates(&data).then_some(Self { data })
+	}
+
+	pub fn lock<'g, 'key: 'g, Key: Keyable + 'key>(
+		&'g self,
+		key: Key,
+	) -> LockGuard<'key, L::Guard<'g>, Key> {
+		let mut first_index = 0;
+		let mut locks = Vec::new();
+		self.data.get_ptrs(&mut locks);
+
+		if locks.is_empty() {
+			return LockGuard {
+				// safety: there's no data being returned
+				guard: unsafe { self.data.guard() },
+				key,
+				_phantom: PhantomData,
+			};
+		}
+
+		let guard = unsafe {
+			'outer: loop {
+				// safety: we have the thread key
+				locks[first_index].lock();
+				for (i, lock) in locks.iter().enumerate() {
+					if i == first_index {
+						continue;
+					}
+
+					// safety: we have the thread key
+					if !lock.try_lock() {
+						for lock in locks.iter().take(i) {
+							// safety: we already locked all of these
+							lock.unlock();
+						}
+
+						if first_index >= i {
+							// safety: this is already locked and can't be unlocked
+							//         by the previous loop
+							locks[first_index].unlock();
+						}
+
+						first_index = i;
+						continue 'outer;
+					}
+				}
+
+				// safety: we locked all the data
+				break self.data.guard();
+			}
+		};
+
+		LockGuard {
+			guard,
+			key,
+			_phantom: PhantomData,
+		}
+	}
+
+	pub fn try_lock<'g, 'key: 'g, Key: Keyable + 'key>(
+		&'g self,
+		key: Key,
+	) -> Option<LockGuard<'key, L::Guard<'g>, Key>> {
+		let mut locks = Vec::new();
+		self.data.get_ptrs(&mut locks);
+
+		if locks.is_empty() {
+			return Some(LockGuard {
+				// safety: there's no data being returned
+				guard: unsafe { self.data.guard() },
+				key,
+				_phantom: PhantomData,
+			});
+		}
+
+		let guard = unsafe {
+			for (i, lock) in locks.iter().enumerate() {
+				// safety: we have the thread key
+				if !lock.try_lock() {
+					for lock in locks.iter().take(i) {
+						// safety: we already locked all of these
+						lock.unlock();
+					}
+					return None;
+				}
+			}
+
+			// safety: we locked all the data
+			self.data.guard()
+		};
+
+		Some(LockGuard {
+			guard,
+			key,
+			_phantom: PhantomData,
+		})
+	}
+
+	pub fn unlock<'key, Key: Keyable + 'key>(guard: LockGuard<'key, L::Guard<'_>, Key>) -> Key {
+		drop(guard.guard);
+		guard.key
+	}
+}
+
+impl<L: Sharable> RetryingLockCollection<L> {
+	pub fn read<'g, 'key: 'g, Key: Keyable + 'key>(
+		&'g self,
+		key: Key,
+	) -> LockGuard<'key, L::ReadGuard<'g>, Key> {
+		let mut first_index = 0;
+		let mut locks = Vec::new();
+		self.data.get_ptrs(&mut locks);
+
+		if locks.is_empty() {
+			return LockGuard {
+				// safety: there's no data being returned
+				guard: unsafe { self.data.read_guard() },
+				key,
+				_phantom: PhantomData,
+			};
+		}
+
+		let guard = unsafe {
+			'outer: loop {
+				// safety: we have the thread key
+				locks[first_index].read();
+				for (i, lock) in locks.iter().enumerate() {
+					if i == first_index {
+						continue;
+					}
+
+					// safety: we have the thread key
+					if !lock.try_read() {
+						for lock in locks.iter().take(i) {
+							// safety: we already locked all of these
+							lock.unlock_read();
+						}
+
+						if first_index >= i {
+							// safety: this is already locked and can't be unlocked
+							//         by the previous loop
+							locks[first_index].unlock_read();
+						}
+
+						first_index = i;
+						continue 'outer;
+					}
+				}
+
+				// safety: we locked all the data
+				break self.data.read_guard();
+			}
+		};
+
+		LockGuard {
+			guard,
+			key,
+			_phantom: PhantomData,
+		}
+	}
+
+	pub fn try_read<'g, 'key: 'g, Key: Keyable + 'key>(
+		&'g self,
+		key: Key,
+	) -> Option<LockGuard<'key, L::ReadGuard<'g>, Key>> {
+		let mut locks = Vec::new();
+		self.data.get_ptrs(&mut locks);
+
+		if locks.is_empty() {
+			return Some(LockGuard {
+				// safety: there's no data being returned
+				guard: unsafe { self.data.read_guard() },
+				key,
+				_phantom: PhantomData,
+			});
+		}
+
+		let guard = unsafe {
+			for (i, lock) in locks.iter().enumerate() {
+				// safety: we have the thread key
+				if !lock.try_read() {
+					for lock in locks.iter().take(i) {
+						// safety: we already locked all of these
+						lock.unlock_read();
+					}
+					return None;
+				}
+			}
+
+			// safety: we locked all the data
+			self.data.read_guard()
+		};
+
+		Some(LockGuard {
+			guard,
+			key,
+			_phantom: PhantomData,
+		})
+	}
+
+	pub fn unlock_read<'key, Key: Keyable + 'key>(
+		guard: LockGuard<'key, L::ReadGuard<'_>, Key>,
+	) -> Key {
+		drop(guard.guard);
+		guard.key
+	}
+}